The world of Searation Science – A Perspective on Chromatography–色谱分离科学角度看世界.pptVIP

CHAPTER 5a:PRINCIPLES AND BASIC THEORY OF CHROMATOGRAPHY Department of Chemistry Faculty of Science Universiti Teknologi Malaysia ANALYTICAL CHEMISTRY SSC 1293 Chromatography The word “chromatography” originated from two Greek words, chroma which means “color” and graphy which means “writing”. Chromatography was founded in 1906 by a Russian botanist, Micheal Tswett, when he separated plant extracts on a column packed with finely divided calcium carbonate. Purpose of Chromatography Chromatography is a method to separate two or more compounds in a mixture based on the differences in the property of each individual substance. The properties include polarity, solubility, ionic strength, and size. Chromatography is today one of the most useful analytical methods for separation, identification, and quantitation of chemical compounds. Principles In chromatography, the compounds are physically separated by distributing themselves between two phases: (a) a stationary phase (b) a mobile phase which flows continuously across the stationary phase. Principles The stationary phase can be (a) a solid packed into a column (b) a solid coating the surface of a flat, plane material (c) a liquid supported on a solid (d) a liquid supported on the inside wall of an open tube The mobile phase can be a gas, a liquid or a supercritical fluid. Principles (cont.) The mixture to be analysed is introduced onto the stationary phase and mobile phase carries the components through it. Each individual analyte interacts with the two phases in a different manner. Principles (cont.) Because analytes differ in their affinity for the stationary phase vs the mobile phase, each analyte exhibits different migration and elution patterns and thus a mixture of analytes can be separated and quantified. The tracing of the output signal vs time or mobile phase volume is called a chromatogram. Classification of elution chromatographic techniques Adsorption C